Subdural Haematoma

A subdural haematoma is a serious medical condition where blood collects between the protective layers of the brain, usually following a head injury. While symptoms can appear immediately after trauma, they may also develop gradually over weeks or even months, making this condition particularly challenging to recognize.

Table of contents

• What is a subdural haematoma?
• Types of subdural haematomas
• Causes and risk factors
• Associated anatomy
• Symptoms
• Diagnosis
• Treatment options
• Recovery and support
• Outlook

What is a subdural haematoma?

A subdural haematoma is a type of bleeding that occurs inside your head. It happens when blood collects between the dura mater (one of the protective layers covering your brain) and the brain tissue itself^[1]. This condition most often results from a head injury and can be life-threatening^[1].

The brain is protected by three layers of membranes called the meninges. The dura mater is the outermost layer, closest to your skull. Beneath it lies the arachnoid mater, and closest to your brain tissue is the pia mater^[1]. When a subdural haematoma develops, blood leaks from a torn blood vessel into the space between the dura and arachnoid layers^[3].

As blood accumulates, it can put pressure on the brain tissue. This pressure may compress and displace brain structures, potentially causing serious damage^[4]. The bleeding typically comes from small bridging veins that connect the surface of the brain to its outer covering. These veins can stretch and tear when the head experiences sudden movement or impact^[3].

• Brain
• Dura mater
• Arachnoid mater
• Pia mater
• Skull
• Bridging veins

Types of subdural haematomas

Healthcare providers classify subdural haematomas based on how quickly they develop and how much damage they cause. There are three main types^[1]:

Acute subdural haematoma is the most dangerous type. Symptoms are severe and appear right after a head injury, often within minutes to hours. The blood pools quickly, causing rapid pressure increase on your brain. Without quick diagnosis and treatment, this type can lead to loss of consciousness, paralysis, or death^[1].

Subacute subdural haematoma develops more slowly than the acute type. Symptoms usually appear hours to days, or even weeks after the head injury. This type can occur alongside a concussion (a mild brain injury)^[1].

Chronic subdural haematoma is more common in people older than 65. The bleeding occurs slowly, and symptoms may not appear for weeks or months after injury. Even a minor head injury can cause this type. Because symptoms develop so gradually, you may not even remember injuring your head^[1].

Subdural haematomas are not uncommon, occurring in around 1 in 4 people with head injuries^[1].

Causes and risk factors

The most common cause of a subdural haematoma is head injury^[4]. This can result from various accidents including car crashes, falls, or violent attacks. The sudden impact strains the blood vessels within the dura, causing them to tear and bleed^[5].

In older adults, the brain naturally shrinks with age, making the subdural space larger. This increased space stretches the bridging veins, making them more likely to tear even from minor injuries^[4]. About one-third of subdural haematomas occur in older adults^[5].

In infants and young children, subdural haematomas can occur as a result of child abuse, particularly in cases of abusive head trauma^[3].

Several factors increase your risk of developing a subdural haematoma^[4][5]:

• Recent head trauma or injury
• Advanced age (over 65 years)
• Taking medicines that thin your blood, such as warfarin or aspirin
• Long-term alcohol use
• Medical conditions that affect blood clotting
• Repeated head injuries, such as from falls
• Previous brain surgery

Symptoms

Symptoms of a subdural haematoma can appear immediately following head trauma or develop gradually over time. The timing depends on the type and severity of the bleeding^[1].

Common symptoms include^[2][1]:

• A severe headache that doesn’t improve with painkillers
• Feeling sick and vomiting
• Confusion and memory problems
• Changes in personality, such as being unusually aggressive
• Drowsiness or feeling very sleepy
• Slurred speech and problems with swallowing
• Vision problems, like blurred or double vision
• Dizziness
• Loss of balance and difficulty walking
• Weakness or numbness on one side of your body

In chronic subdural haematoma, additional symptoms may include memory loss, disorientation, and personality changes^[1].

As bleeding continues and pressure on the brain increases, symptoms can worsen. Severe symptoms include paralysis, seizures, breathing problems, loss of consciousness, and coma^[1].

In babies, a subdural haematoma may cause the head to enlarge because their soft skull can expand as blood collects^[1].

Sometimes people have no symptoms immediately after a head injury. This is called a lucid interval. They may feel fine at first but develop symptoms days later^[1]. Chronic subdural haematomas can be mistaken for other conditions such as brain tumors, stroke, or dementia because symptoms develop so slowly^[1].

You should call 999 immediately if someone has hit their head and has been knocked out and not woken up, has difficulty staying awake, has a seizure, has fallen from a height more than 1 meter or 5 stairs, or has problems with vision, hearing, walking, balance, understanding, speaking or writing^[2].

You should go to A&E if you or your child have had a head injury and have been knocked out but have now woken up, have vomited since the injury, have a headache that doesn’t go away with painkillers, have a change in behavior, or have problems with memory^[2].

Diagnosis

If doctors suspect you have a subdural haematoma, they will perform imaging tests to confirm the diagnosis and assess the severity^[2].

A CT scan (computed tomography) is the most common test used. This scan combines a series of X-ray images taken from different angles to create detailed cross-sectional images of your brain and skull^[4]. The scan can show the location and size of the bleeding.

An MRI scan (magnetic resonance imaging) may also be used, particularly for chronic subdural haematomas. This test uses a strong magnetic field and radio waves to create detailed images of the brain tissues. MRI can help doctors predict which treatment approach will be most effective and assess the likelihood of the haematoma returning^[12].

Your doctor may also check the pressure inside your skull and perform tests to assess your blood’s ability to clot^[5].

Treatment options

Treatment for a subdural haematoma depends on several factors, including the size of the bleeding, how quickly it developed, your symptoms, and your overall health^[2].

If you have a small haematoma that’s only causing mild symptoms, you may be monitored with regular scans and given medicines to reduce swelling in your brain. Some small bleeds may resolve on their own without surgery^[2][5].

However, most people with a subdural haematoma will need surgery to remove the blood and relieve pressure on the brain^[2]. There are two main surgical approaches:

Burr hole drainage: The surgeon drills small holes (called burr holes) in your skull, and the blood is drained out through these holes^[2].

Craniotomy: The surgeon cuts open a section of your skull to remove the haematoma, then seals the cut^[2]. This procedure creates a larger opening in the skull and is typically used for larger haematomas or when more extensive access is needed^[12].

In some cases, particularly for chronic subdural haematomas, doctors may use a newer technique called middle meningeal artery embolization. This involves guiding a catheter into the artery supplying blood to the subdural haematoma and releasing specialized pellets to stop the bleeding^[12].

If you take blood-thinning medicines, you may need to stop taking them. Your doctor may also give you treatment to reverse the effects of these medicines to help prevent further bleeding^[1][2].

After surgery, you may need intensive care for ventilator-dependent breathing, strict blood pressure control, and management of pressure inside your skull^[13].

Recovery and support

Recovery from a subdural haematoma can be challenging, both physically and emotionally. The extent of recovery depends on the severity of the injury and how quickly treatment was provided^[2].

People with serious subdural haematomas can be left with long-term or permanent problems, such as difficulties with walking, talking, and thinking. They may also experience seizures^[2].

You will be supported by a range of healthcare professionals who can offer treatments and therapies to help^[2]:

• Physiotherapy: A physiotherapist can teach you exercises that may make it easier for you to move around
• Occupational therapy: This aims to improve your ability to do everyday tasks
• Speech and language therapy: A therapist can help you with any difficulties you may have with speaking, eating, and swallowing

During recovery, it’s important to get plenty of rest and return to normal activities slowly. You should avoid activities that are physically or mentally demanding, such as housework, exercise, using the computer, or text messaging^[15].

Do not drink alcohol until your doctor says it’s okay, and don’t drive a car, ride a bike, or operate machinery until your doctor gives permission^[15].

In addition to medical support, you may find it helpful to talk to other people whose lives have been affected by brain injury. Your care team may be able to provide information on patient support groups in your area^[2].

Outlook

The outlook for subdural haematoma depends on the type and location of the head injury, the size of the blood collection, and how quickly treatment begins^[4].

Acute subdural haematomas have high rates of death and brain injury, even with the best medical and surgical care. This is largely because they are often associated with extensive underlying brain injury^[8].

Chronic subdural haematomas generally have better outcomes in most cases. Symptoms often improve or go away after the blood collection is drained^[4].

Subdural haematomas can be very serious injuries, and even with the best care, there is a risk of death^[2]. However, with prompt recognition and appropriate treatment, many people can make significant recoveries.

Seizures may occur at the time the haematoma forms or months to years after treatment, but medicines can help control them^[4].

Follow-up care is crucial. You should attend all scheduled appointments and contact your doctor immediately if you experience new or worsening symptoms, such as increased headaches, new weakness or numbness, or changes in consciousness^[15].